1. Field of the Invention
The present invention relates to a method and system for repairing a main memory, and more particularly, to a method and system for repairing a main memory by utilizing a spare memory.
2. Description of the Related Art
With the progress of process technologies, the density and speed of integrated circuits are dramatically improved. However, the tolerance of the new technology to process variation, interference and electromigration becomes worse. Especially for memory circuits whose transistor density is higher than other logic circuits, it is found that the productive yield and reliability thereof decrease with the progress of process technologies. Therefore, it is necessary for the large-scaled memory to conduct a test and repair action to remain in a high yield state.
A well-known repair method is to utilize a spare memory to displace defects in a memory by a mapping table. Normally, one-dimensional or two-dimensional structures, like column or row spare memories are used to displace defects in a memory, based on a fault bitmap in a spare memory redundancy analysis table to conduct a repair action. In term of one-dimensional structure, such structure is too simple to repair two-dimensional defects in large-scaled memories. In term of two-dimensional structure, although such structure can repair two-dimensional defects, the defects which appear closely in row and column directions and form clusters cannot be effectively repaired.
Given that the repair method for a large-scaled memory is significantly important for a large-scaled memory, it is necessary to develop a simple and effective repair method and system.